“Quantum Chance” (Springer, 2014) by Nicolas Gisin is a slim volume about entanglement, quantum nonlocality, and the Bell experiment. (The book was originally published in French in 2012; this review is of the English translation.) Gisin is well known both for his deep interest in the foundations of quantum mechanics and for his experimental expertise. That expertise has made him a pioneer in the practical development of quantum cryptography; but, combined with his insight into quantum theory, it has also allowed him to devise ingenious tests of quantum mechanical predictions. His long consideration of these questions informs every page of this book, where he presents his arguments in a clear and engaging style.

The book begins by postulating a peculiar telephone. Alice and Bob–the heroes of many a paper on quantum information–each have a telephone, which is useless for communication: it produces only random noise. But they discover that the noise produced on the two sides is perfectly synchronized. Being good scientists, they try to determine whether the correlations arise due to communication from one side to the other, or due to some common cause, such as a long random sequence stored identically in each telephone before they were distributed.

From this science fictional scenario we are led to the idea of a Bell experiment: two widely separated experimenters, each equipped with a black box that has two settings and two possible outputs. Gisin lays out the description of a Bell game (actually, the CHSH game), and derives the CHSH inequality that must be satisfied if the two black boxes cannot communicate, but are correlated due to a common cause. He then describes how such a Bell test can be carried out in an actual quantum experiment, and how quantum mechanics predicts that the inequality is violated. This, in the language commonly used in quantum theory, is quantum nonlocality.

From there he presents related concepts from the heart of quantum information: the no-cloning theorem and entanglement. He describes how real world experiments have been designed to test Bell’s theorem, and how all tests to date have supported the predictions of quantum mechanics. He discusses the two major loopholes in experimental Bell tests, the locality and detection loopholes. (This book was written before the three loophole-free Bell experiments done in 2015. Perhaps he will add them to a future edition, since Gisin himself is a major contributor to the study of such loopholes.) He describes his 2008 experiment, which showed that any hidden superluminal communication between the two sides must be many times faster than the speed of light.

There are, of course, philosophical loopholes that are probably impossible to close, such as superdeterminism: the idea that all of Alice and Bob’s choices, as well as the seemingly random outcomes are determined from the beginning of the universe. Gisin briefly discusses a number of related topics, like the Free Will Theorem of Conway and Kochen, and outlines his more recent result (with collaborators Bancal et al.) that proves a remarkable extension of Bell’s theorem. Using 3- and 4-body correlations, they show that if correlations arise from influences propagating at any finite velocity, they must eventually either disagree with the predictions of quantum mechanics or allow superluminal communication (or both).

In addition to its central focus on Bell experiments and nonlocality, the book also discusses some applications of entanglement. There are two fairly brief chapters, one on random number generators and quantum cryptography and one on quantum teleportation, which hint at the large effort now being devoted to quantum-based technology.

The philosophical heart of the book, to which the author repeatedly returns, is this: if quantum mechanics violates Bell inequalities, then the randomness of quantum measurements is not due to ignorance, like the seeming randomness of a tossed coin or of thrown dice. Rather, it must be true randomness: new information that spontaneously appears out of nowhere. Gisin argues that because of its nonlocality, quantum mechanics is inconsistent with a deterministic, Newtonian world view. This argument–like all arguments in quantum foundations–has been disputed, but I have never seen it presented with such cogency as in this book.

While “Quantum Chance” does not assume knowledge of quantum mechanics, and derives all its arguments from first principles, it will not be an easy read for most laypeople. Several early chapters bristle with equations and tables, and the book draws on some math (like binary arithmetic and probability theory) that might be daunting to a mathematically unsophisticated reader. However, it is easily readable by technical readers who are not specialists in quantum theory. They will find it a concise and highly accessible introduction to Bell’s theorem, and to the ideas of entanglement and quantum nonlocality. And specialists will find it interesting as well, as clearly presenting the ideas of one of our deep thinkers about quantum theory.

We also encourage individuals interested in active participation—which typically involves asking questions after the talk—to join the hangout. Otherwise you can watch on the livestream. Details follow.

Title: Size-driven quantum phase transitions

Speaker: David Perez-Garcia, Universidad Complutense de Madrid

Abstract: Most of the theoretical knowledge about quantum many body systems comes from performing numerical simulations. One tries to capture the relevant physical features of a system by extrapolating to the large system size the knowledge obtained in the analysis of an increasing sequence of finite-size systems, which must be small enough for the computer to be capable of giving an answer in a reasonable amount of time. In this work we show simple examples that totally defeat any such approach. More concretely, we construct translationally invariant quantum spin models on the 2D square lattice with reasonably small local dimension exhibiting the following surprising feature that we refer to as a “size-driven phase transition”‘: For all system sizes smaller than a threshold value L, the system has a unique ground state with product structure and a constant spectral gap to the first excited state, which also has product structure. However, for all system sizes larger than L, the system has topological quantum order, meaning a finite number of ground states which are locally indistinguishable, a finite spectral gap and first excited states with anyonic statistics. Moreover, we construct examples (all of them with local dimension smaller than 10) for which the threshold size L can occur at essentially any order of magnitude. From sizes that are reachable within current experimental setups and numerical simulations (L=15 or L=84) to sizes that are beyond any present or future capability, such as L> 10^35000.

The meeting will bring together nearly 10,000 physicists, scientists, and students from all over the world to share groundbreaking research from industry, universities, and major labs. The venue for the conference is the Baltimore Convention Center in Baltimore MD, and runs from March 14th to the 18th. More Information.

Cory, David [2015]
University of Waterloo
Citation: For pioneering one of the first demonstrations of a quantum computer using magnetic moments of nuclei as quantum bits and identifying new industrial applications in medicine, oil exploration and pharmaceuticals.

Englert, Berge [2015]
National University of Singapore
Citation: For distinctive theoretical contributions to the foundations, interpretation, and applications of quantum mechanics.

Nemoto, Kae [2015]
National Institute of Academic Degree
Citation: For pioneering the theory for quantum optical implementations of quantum information processing and communication.

Tahan, Charles [2015]
Lab for Physical Sciences
Citation: For important contributions to the field of quantum information science, including theoretical work advancing the experimental development of silicon quantum computers and proposing new quantum devices in the solid state.

Walther, Philip [2015]
No Company Provided
Citation: For outstanding achievements in experimental quantum information, quantum optics, and quantum photonics; including the first realization of privacy-preserving quantum cloud computing and the first experimental verification of a quantum computation.

In order to celebrate the 90th anniversary of quantum mechanics, the International Journal of Quantum Foundations (IJQF), will host an online Workshop on Quantum Foundations from 9th July 2015 to 19th July 2015. The workshop will bring together leading experts in the field, and address the most pressing problems in the foundations of quantum mechanics today.

Based on the successful experience from First iWorkshop on the Meaning of the Wave Function and John Bell Workshop 2014, this workshop will be more self-organized. Every participant may create a topic in the workshop forum on his own, which attaches his paper and gives a concise introduction to his ideas to be discussed, and which also states the date and time of his two-hour discussion. Then other participants can leave comments beforehand or participate in the discussions by text chat in the forum in the two-hour duration at the time.

After much delay, it is my pleasure to announce the newest incarnation of The Quantum Times. In its new format, readers can submit articles, conference announcements, and job postings (see “Submit A Post” tab above) that will then be reviewed, possibly edited, and finally posted. Any major edits will be cleared with the author prior to posting. The aim is to dramatically speed up the time it takes for an item to appear in The Times. The only drawback is that there will no longer be regular issues. Rather, it will be a “continuous” publication.

The key is for The Times to become a community site for quantum information and foundations, and to encourage active participation in the APS’ GQI, which is very close to attaining division status. As GQI is the world’s largest organization dedicated solely to quantum information, this represents the natural evolution of The Times which started out as the group’s newsletter in 2006.

We would like to thank Matt Leifer for his technical assistance with setting this site up. We would also like to thank the Executive Committee and Editorial Board for their support and patience during this transition.

Remember that this site relies on your submissions! We look forward to hearing from you!

Postdoc positions available at the University of New South Wales in Sydney, Australia

Silicon Quantum Computing

The research will investigate the controlled coupling of multi-qubit devices, and the coherent transport of quantum information. Experiments will involve the configuration and operation of high-frequency electronics compatible with cryogenic measurements.

Applications are sought from technically talented candidates with an ambition to create atomic-scale devices in silicon or germanium via high resolution STM-lithography and advanced semiconductor clean-room processing.

The 12th International Workshop on Quantum Physics and Logic (QPL) will take place at the Department of Computer Science of the University of Oxford between Wednesday 15 and Friday 17 July, 2015. The workshop will be preceded by tutorials on Monday 13 and Tuesday 14 July 2015.

This workshop brings together researchers working on mathematical foundations of quantum physics, quantum computing, spatio-temporal causal structures, and related areas such as computational linguistics. Of particular interest are topics that use logical tools, ordered algebraic and category-theoretic structures, formal languages, semantical methods and other computer science methods for the study of physical behaviour in general.

Submission Deadline: May 1, 2015
Notification of Acceptance: June 1
Papers Ready: June 15
Tutorials: July 13-14
Workshop: July 15-17

SUBMISSIONS

Prospective speakers are invited to submit a contribution to the workshop.

*Short contributions* consist of a 3 page description of the work, and a link to a paper published elsewhere.

Longer *original contributions* consist of a 5-12 page extended abstract which provides sufficient evidence of results of genuine interest and provides sufficient detail to allow the program committee to assess the merits of the work. Submissions of works in progress are encouraged but must be more substantial than a research proposal.

Extended versions of accepted original research contributions will be published in Electronic Proceedings in Theoretical Computer Science (EPTCS) after the workshop.

There will be an award for the best paper whose authors are all students, at the discretion of the programme committee.

REGISTRATION

Please visit the website to register. We encourage participation by graduate students, and will be able to provide limited reimbursement to partially support students for travel and accommodation. Further information is found on the workshop website.